Scriber



Feb. 5, l Ab E RAWALD l I SCRIBER Filed July 15, 1943 1 l N ,(1 I @mi 4T@ ATTO R N EY Patented Feb. 5, 1946 SCRIBER vAugust E. ,RawallL lMdland Park, N. J., assigner Ato Wright Aeronautical Cor-poration, a corporation of New York .Applicaiiipn .3T U15' 16, 1943, Serial N0.495,'006

( Cl. iS-42g) .2 Claims.

This invention relates to a marker :or scriber for .drawing circles and is particularly useful for drawing fcircles on .a face of an annular `shaped object.

In .the past when 'it was desired-to drawa-circle about an opening, for example, iin :order to provide a marking circle for vrnachining operations it was the practice to support the article in -a lathe in order to scribe the desired circle. `Obviously, conventional -compasses could not be used for this purpose because of the absence of material at the center of the circle. It is an object of this invention to provide a simple tool adapted to mark or scribe a circle on the face of an annular object. It is a further object of this invention to provide a tool for marking or scribing a circle without the need of a pivot point at the center of the circle.

Specifically, the circle scriber of this invention comprises a tool having a pair of diverging arms and an intermediate arm adapted to lie across the surface upon which the circle is to be drawn. The intermediate arm is arranged to adjustably support a scriber or marking element and the diverging arms are adapted to engage the periphery of the object upon which the circle is to be drawn.

Other objects of this invention will become apparent in reading the annexed detailed description in connection with the drawing in which:

Fig. 1 is a plan View of an annular object upon which a circle is to be drawn,

Fig. 2 is a plan view of the object with the tool embodying this invention in position thereon for drawing a circle,

Fig. 3 is a side elevation of Fig. 2, and

Fig. 4 is an enlarged section on line 4--4 of Fig. 1.

Referring to the drawing, the tool hereinafter described is adapted to draw concentric circles of various diameters on the face end of annular objects of various sizes, for example, the article or plate I illustrated in Fig. 1. If a plurality of circumferentially spaced holes are to be drilled in the plate I5) on the circle I2 concentric with the bore I4 and periphery I6 it is necessary to scribe or otherwise mark the circle I2 on the face of the plate Il). Obviously, because of the annular nature of the plate I it is impossible to use conventional Compasses for this purpose. In the past it has been customary to rotate the plate 4I) in a lathe in order to draw such a circle.

The circle-marking instrument of this invention comprises a pair of diverging arms I8 and an elongated intermediate arm 20.pre*fera3blyf-bl secting the angle between ,the arms 1B. of the arms I8 is provi-,ded a'roller 22 pivotally mounted therepn by a shaft or lbolt 24. Suitable bearing means may be provided ibetween each shaft "24 and its 'associated roller to take up all clearance and provide for jffree rolling action. When the rollers h22 are pla-ced Vin contact with the outer lcircular periphery II6 -of Jthe 'annular plate I0 all points on the intermediate arm 2U are always at the same distance Lfrom Ithe center of the circular periphery -I6 regardless of Vthe location of the diverging arms I8 about this periphery. Therefore, any point on the intermediate arm 20, oiset from the center of the annular plate, will describe a circle about this center as the arms I8 are rotated about and in contact with the outer periphery I6 of the plate II).

In order to mount a scriber or marker on the arm 23 an elongated rod 2B is suitably supported above the surface of the arm 2D and parallel thereto. A bracket member 28 is adjustably supported along this rod by means of a set screw 30. This bracket 28 is provided with a flat under surface adapted to slidably engage the fiat upper surface of the elongated arm 20, thereby preventing any turning movement of the bracket 28 about the rod 26. The free end of the bracket 28 is bifurcated and a supporting lever 32 is pivoted at 33 between the bifurcated ends of the bracket 28. A dovetail slot 34 is provided in the upper portion of the lever 32 for receiving a marker or scriber carrying arm 3'u`. A set screw 38 rigidly secures the arm 36 within the dovetail slot 34 and a spring 4I] is disposed between the bracket 28' and the arm 3E to upwardly bias the free end of the arm 3S. A scriber or marker 42 having a pointed marking end is adjustably secured to the arm 3B by a set screw 44.

As illustrated in Fig. 4 the pointed end of the marker or scriber 42 is disposed to the left of the pivotal support 33 whereby the spring 4B urges the marking point into contact with the surface of the point lil. In this way the scriber element is resiliently supported in contact with the surface of the plate I0 when the circle-scribing instrument is in operative position relative to the plate. For marking purposes the surface of the plate I0 may be coated with a suitable ink Which is adapted to be removed by the sharp point of the scriber element. Upon relative rotation of the plate I0 and the circle-marking instrument the pointed marking element 42 will describe a circle on the plate I0 of a rdiameter correspond- Vas conventional Compasses.

' also has a flatlower side engaging the surface of the plate I to help maintain the surface of the plate l0 in parallelism With the circle-describ-V ing instrument While the instrument is rotating relative to the plate for marking a desired circle.v

The circle-marking scribed is quite simple and'can be` used as easily This novelfcirclemarking instrument is particularly useful for instrument herein deat surfaced object having Va circular periphery,

marking concentric circles on the surface .of ,an 'f annular object. The instrument is adjustablefor marking circles of Various diameters and obviouslyis adapted for usewith annular objects of various sizes. Y f

4While I have described my invention in detail in its present embodiment, it Vwill be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit orscope thereof. I aim in the appended claims to cover all such modifications and changes. g

I claim as my invention: 1. An. instrument for drawing circles upon a said instrument comprising a pair of divergent arms, the free ends of said arms being provided with bearing means for engagement with said circular periphery, an intermediatearm secured to said divergent arms, said intermediate arm" having a atrside' adapted to lie across and 1n contact with the at surface of said object 'with 'K said bearing means in engagement with said circular periphery,V a scriber member mounted for adjustment along said intermediate arm,y and spring means operative to resiliently urge said scriber element into contact with said surface when said intermediate arm is disposed inV con- Y tact therewith. Y Y

2. An instrument for marking on the surface of an object, said instrument comprising a pair of diverging arms adaptedV to engage the Vperiphery of said object, an intermediate arm iixed to said pair of arms and having a at side adapted to lie across said surface, a member mounted on said intermediate arm for pivotaly movementV l relatively thereto and for adjustment therealong, a scriber elementcarried by said member, and spring means urging pivotal movement of said member for maintaining said scriber element vin contact with said surface inthe operative position of said instrument. 1 f

' l YAUGUSTv E. RAWALD. 

